Boston Scientific Corp. (BSX) said its first-quarter profit rose 85 percent as the medical device maker extended a more than yearlong profit surge on sales of its market-leading drug-coated heart stent (search).

The company said, however, that it expects sales growth to return to more moderate levels in the coming quarters.

The Natick-based company on Tuesday reported net income of $358 million for the January-March period, or 42 cents per share, compared with a profit of $194 million, or 23 cents per share, in last year's first quarter.

Sales rose to $1.62 billion, up 49 percent from $1.082 billion a year ago.

The profit was reduced by $73 million in expenses related to Boston Scientific's acquisition of Advanced Stent Technologies (search). Excluding the charges, Boston Scientific's profit came in at $431 million, or 51 cents per share, matching the consensus estimate of analysts surveyed by Thomson Financial.

Boston Scientific's shares dropped 59 cents, or 1.9 percent, to $30.16 Tuesday on the New York Stock Exchange. The shares have traded in a 52-week range of $28.56 to $45.76.

The 85 percent net income growth last quarter followed four consecutive quarters in which Boston Scientific's profit has at least doubled. The surge is largely attributed to Boston Scientific's hottest product, the Taxus Express2 (search) stent, which is coated with drugs to help prevent buildup of scar tissue after artery-clearing surgery.

Sales of the stent rose 219 percent last quarter to $686 million, including $494 million in U.S. sales.

The metal-mesh device, approved for U.S. use in March 2004, a year after its European introduction, commands about two-thirds of the drug-coated stent market. A rival stent from a unit of Johnson & Johnson holds a one-third market share, with other rivals including Medtronic and Guidant hoping to enter the market as well.

"In the coming quarters, we expect our recent dramatic growth to return to more moderate levels, following a full year of Taxus system sales in the United States," said Jim Tobin, president and chief executive.

The company did not offer forecasts of future earnings. Analysts forecast a profit of 51 cents per share for the second quarter and $2.09 for the full year.